Zusammenfassung der Ressource
Computer Systems
- Importance
- Improved quality in manufacturing - robotic
machinery is more accurate than humans
- Cheaper manufacturing -
automation reduces wage
costs and allows 24/7 working
- Faster access to information - many jobs can be done more quickly
- Better decision making - with lots of facts organised
and available, decisions can be better informed
- New ways of doing business - more buying online, more choice, cheaper goods; facilities
such as the internet and ATMs would not be possible without computer systems
- New ways of communicating - email, SMS,
cell phones - are being developed all the time
- Examples
- Satnav
- Inputs: signals
from satellites,
inputs from user
- Outputs: route, places of interest, warnings
- Processing: check
position, locate on
map, output map
- Car engine
management
- Inputs: temperature, CO2 levels, speed
- Outputs: signals to carburettor,
data to engine diagnostics
- Processing: check values against
set parameters, produce fault codes
- Holiday booking
- Inputs: dates, destination,
credit card details
- Outputs: itineraries, air
tickets, hotel reservations
- Processing: check availability,
produce documents
- Types
- General-purpose systems, such as laptops and
smartphones, are designed to perform multiple
tasks (various applications can be loaded)
- Dedicated systems are specially produced to perform a
single function, for example a ticket-vending machine
- Control systems control machinery rather
than produce outputs for humans to
respond to. Important in manufacturing
processes but also in domestic gadgets.
- Industrial robots are an
important application of
control systems.
- Embedded system are part of a larger system. They include portable devices: digital watches,
satnavs, cameras, and larger installations: traffic lights, controllers of machinery in factories
- Can be simple or highly complex (most cars have up to
50 systems looking after fuel flow, window control, etc.)
- Expert systems
are designed to
behave like a
human expert.
- They have three component parts: a
knowledge base (a database of facts), an
inference engine (software that makes
deductions using the knowledge base) and
an interface (to allow human access)
- Commonly used for: diagnosing diseases, finding
faults in machinery, choosing complex products
(mortgages, insurance policies), making credit checks
and suggesting purchases to coconsumers
- Management information
systems bring together the
information from all parts of an
organisation so that managers
can make sensible decisions
- They cover: technology, data, and people, and typically
produce regular reports based on the organisation's data
- Examples: Decision Support Systems are used by middle management to support day-to-day decision making,
Executive Information Systems produce reports using data from throughout an organisation and support decisions
about the organisation's strategy, Office Automation Systems automate workflow and maximise the efficiency of
data movement, School Management Information Systems deal with school administration, teaching and learning
- Reliability
- Mistakes in design can lead to:
down time, expensive errors, data
loss, and compromised privacy
- Computers are central to many
life-or-death situations; aircraft
navigation, railway signalling,
diagnosis of diseases, robotic
surgery, DNA sequencing
- Also refers to data integrity - data being accurate and
consistent (stored data reflects real-world reality)
- Data integrity can be compromised by: human
errors, software bugs, viruses and other malware,
hardware malfunctions, natural disasters
- Ways to reduce risks to data: backing up data regularly, controlling access to data
via security mechanisms, using validation rules to prevent the input of invalid
data, using error detection and correction software when transmitting data
- Reliability is improved by thorough testing but it can never be complete
because software is so complex and testing is expensive and time consuming
- Standards
- Important because they enable equipment from different
manufacturers to work together, make learning systems
easier, minimise waste, help ensure fair play and access to
markets, bring costs down by opening markets to competition
- They exist for
programming languages,
operating systems, data
formats, communication
protocols and electrical
interfaces
- Types of
Standards
- De facto standards (develop over time and ensure that systems can
be used by everyone); PostScript, QWERTY keyboard, Microsoft Word
- De jure standards (by law; so universally accepted
that they have to be adhered or communication is
impossible); ASCII, PDF, Unicode, TCP/IP
- Proprietary standards (owned by organisation to ensure compatibility between
products and reduce competition (e.g. Apple locks users into using their software
and Windows has the same 'look and feel' to make learning them easier
- Industry standards are set by non-commercial organisations (ANSI
- programming languages, ITU - communication protocols, ISO)
- Open standards are produced collaboratively and are
publicly available, not for profit and sufficiently detailed
to allow interoperability. They ensure that access isn't
dependant on a single application or particular hardware
platform. (World wide web, HTTP, HTML)
- Ethical and
Legal Issues
- Data protection
- Typical laws state that organisations must protect data
from unauthorised access, allow people to view data held
about them, and correct information when requested
- Is needed because it's easy to copy, transmit and
match data and make judgements about people
- To do with privacy, data security,
copyright, and terrorism
- Environmental issues
- Waste of obsolote computers can mean toxic chemicals (lead, cadmium) can
leach out into the soil in landfills, especially when E-waste is shipped to
developing countries. Also release dangerous chemicals (dioxins) when burnt.
- Use a lot of energy which can be reduced by using solid state storage rather than rotating disk
drives, modern screens which are less energy insensitive, and automatic standby switching